linux-kernel - [PATCH v2] drm/imx: imx-ldb: Accept drm_of_find_panel_or

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Message-ID: <02532be0049e69fe8e9f8da04fbbcf813d250a39.1494419445.git.leonard.crestez@nxp.com>
Date:   Wed, 10 May 2017 16:17:13 +0300
From:   Leonard Crestez <leonard.crestez@....com>
To:     Philipp Zabel <p.zabel@...gutronix.de>,
        Rob Herring <robh@...nel.org>, David Airlie <airlied@...ux.ie>
CC:     Leonard Crestez <leonard.crestez@....com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Sean Paul <seanpaul@...omium.org>,
        Archit Taneja <architt@...eaurora.org>,
        Liu Ying <gnuiyl@...il.com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Steve Longerbeam <steve_longerbeam@...tor.com>,
        Peter Senna Tschudin <peter.senna@...labora.com>,
        Cristina Ciocan <cristina-mihaela.ciocan@....com>,
        Octavian Purdila <octavian.purdila@....com>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] drm/imx: imx-ldb: Accept drm_of_find_panel_or_bridge failure

Not having an endpoint bound in DT should not cause a failure here,
there are fallbacks. So explicitly accept a missing endpoint.

This behavior change was introduced by refactoring in drm_of parsing
code and it should not require dts changes.

In particular this fixes imx6qdl-sabreauto boards.

Link: https://lists.freedesktop.org/archives/dri-devel/2017-May/141233.html
Fixes: ebc944613567 ("drm: convert drivers to use drm_of_find_panel_or_bridge")
Signed-off-by: Leonard Crestez <leonard.crestez@....com>

---

This relies on drm_of_find_panel_or_bridge returning -ENODEV
specifically if no remote is found for the endpoint. This behavior can
be seen by looking at the code but is not otherwise obviously
guaranteed.

Perhaps this should be explicitly mentioned in that function's
documentation?

Changes since v1:
* Fix returning if ret is 0.

 drivers/gpu/drm/imx/imx-ldb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
index 8fb801f..8b05ecb 100644
--- a/drivers/gpu/drm/imx/imx-ldb.c
+++ b/drivers/gpu/drm/imx/imx-ldb.c
@@ -673,7 +673,7 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
 		ret = drm_of_find_panel_or_bridge(child,
 						  imx_ldb->lvds_mux ? 4 : 2, 0,
 						  &channel->panel, &channel->bridge);
-		if (ret)
+		if (ret && ret != -ENODEV)
 			return ret;
 
 		/* panel ddc only if there is no bridge */
-- 
2.7.4